This is the editor.action.showHover
command. It is bound to cmdk cmdi by default.
Note: Shortcut works by holding down the cmd [ctrl in windows], then while holding press k then i
You can change the keyboard shortcut with a keybinding such as:
{
"key": "cmd+k ctrl+space",
"command": "editor.action.showHover",
"when": "editorTextFocus"
}